soumya92/barista

// Copyright 2018 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

/*
Package timing provides a testable interface for timing and scheduling.

This makes it simple to update a module at a fixed interval or
at a fixed point in time.

Typically, modules will make a scheduler:
    mod.sch = timing.NewScheduler()
and use the scheduling calls to control the update timing:
    mod.sch.Every(time.Second)

The Stream() goroutine will then loop over the ticker, and update
the module with fresh information:
    for range mod.sch.C {
      // update code.
    }

This will automatically suspend processing when the bar is hidden.

Modules should also use timing.Now() instead of time.Now() to control time
during tests, as well as correctly track the machine's time zone.
*/
package timing // import "barista.run/timing"

import (
    "time"

    "barista.run/base/watchers/localtz"
)

// Now returns the current time, in the machine's local time zone.
//
// IMPORTANT: This function differs from time.Now() in that the time zone can
// change between invocations. Use timing.Now().Local() to get a consistent
// zone, however note that the zone will be the machine's zone at the start
// of the bar and may be out of date.
func Now() time.Time {
    mu.Lock()
    defer mu.Unlock()
    var now time.Time
    if testMode {
        now = testNow()
    } else {
        now = time.Now()
    }
    return now.In(localtz.Get())
}